1. Field of the Invention
The present invention relates to a semiconductor wafer tape laminating system and to a method of laminating a semiconductor wafer with a protective tape. More particularly, the present invention pertains to dealing with the edge of adhesive tape protruding from a wafer, the front surface of which is protected by the tape, to prevent the edge from adhering to the wafer or to a piece of processing equipment when it is removed.
2. Description of the Related Art
Generally, the back surface of a semiconductor wafer is not used by the final semiconductor device. Therefore, during the manufacture of the semiconductor device, the back surface is ground to make the wafer as thin as is practical. The front surface of the wafer is laminated with tape prior to the backgrinding of the wafer in order to protect it from grinding water used during the backgrinding process or from wafer dust produced by the backgrinding process. The tape used in this situation is a special adhesive tape which loses its adhesive strength when it is irradiated with a light (for instance, ultra-violet rays) of a predetermined intensity and energy. The light hardens a photosensitive portion (for instance, a photoinitiator) of the tape. Consequently, the UV tape can be easily removed from the front surface of the wafer after the backgrinding process is completed.
The semiconductor wafer tape laminating system also cuts off an edge of the UV tape which protrudes beyond the peripheral edge of the wafer, and then transfers the wafer to the backgrinding station.
Such a laminating system includes a loading device for conveying a wafer or cassette to a predetermined location where the wafer is laminated, a laminating device for pressing the UV tape onto the front surface of the wafer, a precutting device for cutting the UV tape from around the wafer after it has been attached to the front surface thereof, a wire cutting device for removing an edge of the UV tape which protrudes beyond the peripheral edge of the wafer, and an unloading device for carrying the wafer from the wire cutting device.
A knife of the precutting device roughly precuts the UV tape after it attaches to the front surface of the wafer so as to separate the roughly cut portion of the tape, and hence the wafer, from the remainder of the tape. The edge of the UV tape remaining after this precutting is completely removed by a preheated wire of the wire cutting device.
However, the edge of the UV tape removed by the wire cutting device can attach itself to the back of the wafer. If not responded to, this portion of the tape will cause the wafer to crack or break during the backgrinding of the wafer. The edge of the UV tape could also attach itself to other wafers or to various pieces of the manufacturing equipment, resulting in an operation failure. Pieces of the tape which attach themselves to the heated wire of the wire cutting device prevent the wire cutting device from cutting properly. If the piece or pieces stick to the wafer chuck or carrier, they can become adsorbed by the wafer and thus become a source of wafer contamination.